Such a link, as shown in FIG. 1 where it is referenced 1, comprises a generally tubular hollow main body 2 that is extended at each of its ends by a clevis, the clevises being given references 3 and 4 in this example.
Each clevis 3, 4 comprises two prongs referenced 3a & 3b and 4a & 4b, all of which are constituted by a thickness of composite material that is greater than the nominal thickness of composite material in the remainder of the link. The two prongs of each clevis extend parallel to the general direction AX of the hollow main body, and each prong includes a bore in which a metal bearing is mounted.
In a method known from patent document FR 2 893 532, the link is fabricated from a piece of reinforcing fiber fabric that is cut to have a shape as shown in FIG. 2.
This shape comprises a central portion for the hollow main body 2 and four extensions, each corresponding to a respective clevis prong.
The fabric used is a carbon fiber fabric of constant thickness, and it is of the two-and-a-half-dimensional (2.5D) type, i.e. it comprises a plurality of layers of superposed woven fibers, which layers are linked to one another by linking fibers also referred to as transverse fibers.
The fabrication of that link consists in folding the FIG. 2 piece of fabric around a mandrel or the like, and then injecting resin into the reinforcing fiber fabric and then baking the assembly in order to polymerize the resin.
The thickness of the clevises is increased before the fabric is shaped, by cutting the interlinking fibers of the base layers of the 2.5D fabric in the clevises so as to separate the base layers locally from one another.
Intermediate layers are then inserted locally between the separated base layers, thereby enabling the thickness to be increased locally. After adding the intermediate layers, so-called “transverse” fibers are passed through the assembly in order to secure all of the layers to one another.
The prongs of each clevis are thus of thickness that is significantly greater than the thickness of the remainder of the link, thereby increasing the mechanical strength the clevis can oppose against the forces exerted along the direction AX. These forces are the result of the normal loading of the link when its clevis is mounted on a pin (not shown in the figures).
In practice, although that method of fabrication is satisfactory in terms of the mechanical strength of the resulting link, it is nevertheless constraining in terms of its implementation insofar as it depends very greatly on the know-how of the operator performing it.
Parts are also known that are fabricated with the help of a hollow mandrel that is passed through the central orifice of a braiding machine so as to cover the mandrel in one or more layers of braided fibers. A resin is then injected into the assembly and polymerized.
Nevertheless, the braiding method gives rise to constraints on the design of the parts, which parts must in particular avoid having any sudden changes of section.
Unfortunately, with parts that are highly stressed, it is common practice for them to have local extra thicknesses in stress-concentration zones. This applies in particular to landing gear rocker levers that need to include bearings for receiving an axle. The bearings project on either side of the body of the rocker lever and they co-operate with the body to form transition zones having a sudden change of section. Such a rocker lever can be made by braiding only with a mandrel that presents little variation of section and that would require an extra thickness of material to be provided over the entire part, thereby increasing its weight and its bulk.
Proposals are made in document FR 2 890 591 to provide a part having a fiber preform that is reinforced by strips of preimpregnated single-directional fiber fabric extending in a longitudinal direction of the part in order to reinforce said parts, in particular in compression.
Nevertheless, putting such strips into place is very difficult in terms of ensuring that a proper orientation and density of fibers is conserved in order to guarantee the mechanical strength of the part. Unfortunately, there is a considerable risk of geometrical defects that are associated with cutting errors, and with shaping and handling errors.